#include <iostream>

class Test
{
public:
    Test(int a,int b):m_a(a)//参数初始化列表
    {
        m_b = b;
    }

    void show()
    {
        std::cout<<m_a<<std::endl;
    }

private:
    int m_b;
    const int m_a;
};


int main()
{
    Test s(10,20);
    s.show();
    return 0;
}